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51.
Summary Convex programming techniques were used by Witting and Krafft in [4] in order to reduce a testing problem for composite hypotheses to one for simple hypotheses. This is realized in terms of least favourable pairs of distributions, which represent the solution of the dual of a suitable program. Without further assumptions on the hypotheses, however, the results, derived that way (cf. Baumann [1], Österreicher [6] and Kusolitsch and Österreicher [5]), are of less practical impact. This is due to the fact that in this case the least favourable pairs depend on the level of the testing problem. Conditions avoiding this, were given by Huber and Strassen in [3]. These conditions make use of 2-alternating capacities in the sense of Choquet. The present paper offers a rather general principle of constructing the least favourable distribution in the case, when one of the two hypotheses is simple. This method works also for the local variation model and the Prohorov neighbourhood model in the case of monotone likelyhood ratio. For simple cases—subsuming the gross error model and the total variation model, for which the solution was given by Huber in [2]—a least favourable pair is obtained by using the mentioned technique of construction two times successively. 相似文献
52.
N. C. van de Merbel M. Stenberg R. Öste G. Marko-Varga L. Gorton H. Lingeman U. A. Th. Brinkman 《Chromatographia》1995,41(1-2):6-14
Summary A two-dimensional, column liquid chromatographic system is used for the determination of the D- and L-enantiomers of amino acids in biological samples. Separation of the amino acids is first on ion-exchange column by gradient elution with a sodium citratesodium chloride buffer. Enantioseparation is by subsequent injection of 3 l heart-cuts of the individual amino acids onto a second column with a chiral crown ether stationary phase. Finally, fluorescence detection is after post-column labelling of the amino acids using ano-phthalaldehyde-2-mercaptoethanol reagent solution. The high separation power and selectivity of the system allow processing of complex samples with hardly any additional treatment and the determination of small quantities of D-amino acids in the presence of excess L-form. Applicability of the system is illustrated by the determination of D- and L-aspartate, serine, glutamate and alanine in various complex biological samples, such as protein hydrolysates, urine and biotechnological and food samples. Data are given on detectability, repeatability and linearity. 相似文献
53.
Investigation of potential-sensitive fluorescent dyes for application in nitrate sensitive polymer membranes 总被引:2,自引:0,他引:2
Gerhard J. Mohr Frank Lehmann Ralf Östereich Ivana Murkovic Otto S. Wolfbeis 《Analytical and bioanalytical chemistry》1997,357(3):284-291
The applicability of various potential-sensitive dyes (PSD) for optical sensing of anions is reported. Specifically, nitrate-responsive
polymer membranes have been developed which are composed of a plasticized polymer, an anion exchange catalyst, and a fluorescent
dye. On exposure to nitrate, the fluorescence intensity of such membranes increases, while the wavelengths of the excitation
and emission maxima remain virtually unchanged. The membranes typically are 2–4 μm thick and exhibit highest sensitivity to
nitrate in the 2 to 200 mgl–1 range. Signal changes on exposure to 100 mmol/l nitrate can be as high as +300%. The detection limit is 0.2 mgl–1. The cationic PSD octadecyl acridine organe was tested in combination with a tin-organic and an indium-organic anion carrier
rather than with tridodecylmethylammonium chloride, but both carriers were found to display no improved selectivity.
Received: 2 December 1995 / Revised: 28 March 1996 / Accepted: 5 April 1996 相似文献
54.
The binary system Li2Se-In2Se3 was investigated in the range of 40 to 100 mol% In2Se3 by thermoanalytical and X-ray methods. The system is characterized by two eutectic points. Beside the two binary components
and the known ternary compound LiInSe2 another ternary compound crystallizes in this binary system at 83.3 mol% In2Se3. This compound was identified as LiIn5Se8. In contrast to (Cu, Ag)IB5
IIIC8
VI compounds such as CuIn5S8 [1] it does not crystallize in the spinel structure. LiIn5Se8 shows a stratified structure. The melting point was determined to be at 810°C. Starting from room temperature up to the melting
point no phase transitions were observed.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
55.
56.
N. Öztürk T. Akyüz A. Y. Erkol 《Journal of Radioanalytical and Nuclear Chemistry》1995,201(5):439-446
The Eskiehir-Beylikahir district has the largest and richest thorium and rare earth elements deposits in Turkey. The uranium and thorium concentrations of samples taken from four different parts of this area have been determined by the delayed neutron counting technique. The results are compared with those of previous analyses by other techniques and found to be in good agreement. 相似文献
57.
Cabergoline (CAB) is an ergot alkaloid derivative with dopamine agonist activity. A novel, simple, and rapid stability-indicating high-performance liquid chromatographic (HPLC) method for assay of CAB in tablets has been developed and validated. Chromatography was performed on a 4.6 mm i.d. × 250 mm, 5 μm particle, cyano column with acetonitrile–10 mM phosphoric acid, 35:65 (v/v), containing 0.04% triethylamine, as mobile phase, at a flow rate of 1.0 mL min?1, and UV detection at 280 nm. Response was a linear function of concentration in the range 0.1–4 μg mL?1 (r 2 = 0.9999). The recovery of the method was good (99.45%) and RSD values for intra-day and inter-day precision were 0.24–0.88% and 0.66–1.19%, respectively. The method can be used for quality-control assay of CAB in tablets, for stability studies, and for in vitro dissolution studies. 相似文献
58.
Reactions with Organophosphorus Compounds, 49. Synthesis and 1H NMR Spectra of (3-Acylbicyclo[2.2.1]hept-5-en-2-yl)phosphonates Reaction of the (E)-(β-acylvinyl)phosphonates 1 with cyclopentadiene yields the isomeric norbornylphosphonates 2 (endo-acyl, exo-P) and 3 (exo-acyl, endo-P) in a 7:3 ratio. With 1,3-cyclohexadiene the corresponding bicyclooctenyl derivatives 7 and 8 are obtained from 1a . The (Z)-phosphinylacrylate 4 gives with cyclopentadiene the isomers 5 (exo-CO2Me, exo-P) and 6 (endo-CO2Me, endo-P) in nearly equal amounts. The configuration of the cycloadducts has been proved by 1H NMR spectroscopy. 相似文献
59.
The NMR enhancement factor of a frozenCuMn spin glass has been measured at a temperatureT?T g /5. The measurements were performed as function of static magnetic fields of different directions. A two component model of a spin glass has been outlined. One component being a “system of single spins” and the other one being a “subsystem of clusters”. Both components were attributed to different kinds of interaction being RKKY and dipole interaction respectively. The effective anisotropy field of the single spin system consists of two unidirectional contributionsH a s andH a c , which have been measured for different conditions. A second anisotropy fieldH d binds the cluster system to the system of single spins. All anisotropy fields depend on the annealing temperature of the alloys. 相似文献
60.
A photocurable acrylate matrix nitrate-sensitive membrane containing 2-nitrophenyl n-octyl ether as mediator and tetraalkylammonium nitrate as an active compound is described. The photocuring was achieved by the use of photoinitiators containing diaryliodonium chloride. This acrylate membrane is patternable via a photolithographic process with a only slight loss of electrochemical characteristics. 相似文献